Hoist.



UNTTED sTATEs PATENT oEErcE.

MERRILL DAVIS, 0F WATERTOWN, NEW YORK, .ASSIGNOR TO JAMES B. WISE, 0F WATERTOWN, NEW YORK.

HOIST.

To all whom it may concern.vv

Be it known that I, MERRILL DAVIS, a citizen of the United States, residing at Watertown, in the county of Jeerson and State of New York, have invented certain new and useful Improvements in Hoists, of which the following is a specification.

This inventionI relates to that class of pressure operated cylinders or devices, commonly known as hoists or lifts, which are chiefly employed for lifting or moving heavy bodies.

The chief object of my invention is to provide a hoist of the class, which is simple, convenient and durable, and wherein the construction and arrangement of the parts are such that, a steady non-intermittent movement is obtained at every stage of its operation, and which is capable of being controlled to the finest degree of accuracy for accomplishing better work, and at the same time insuring greater safety, than any of the older styles or makes of hoists, known to me.

The features and parts of the invention will be understood from the detailed description which follows, and by reference to the accompanying drawings, which form a part of this specification, and in which- Figure 1 is a central longitudinal section through the hoist; showing the construction and arrangement of the parts of the device; also showing the hoist in fully closed position ready for operation. Fig. 2 is a similar sectional view; showing the hoist extended to its full extent for completing a hoisting operation. Fig. 3 is a sectional view of thevalve which controls the hoist. Fig. 4 is a cross-section, on line 4 4: of Fig. l.

Compressed air is extremely searching, and-a common diliiculty attending the use of compressed air as a medium for operating hoists is that, it is practically impossible to construct the cylinders and the various joints in the supply pipes, so that they will not leak and continually waste the pressure, which renders the operation of the cylinders somewhat unsteady and uncertain. Furthermore, owing to the difference in the kinds and natures of the metals comprising the working parts of the hoists, the variations in the character and tension of the packings, and the different conditions of lubrication, there is also more or less fric- Speccaton of Letters Patent.

Application filed September 9i, 1911.

Patented May 7, 1912.

Serial No. 648,519.

tion to contend with. The principal effect of all these conditions is to give to the hoist an intermittent and jerky motion during both 'the upward and downward travel of the movable parts of the hoist, which occasions unsatisfactory results in the operations of the hoists, which is frequently attended with damage to the machines, and sometimes injures -the operators, or causes loss of life. Heretofore, the common method of overcoming this jerky or intermittent motion of the hoists, has been to provide an auxiliary cylinder charged with a heavy fluid, such as oil, the oil being supplied to both sides of the piston, and the opposite ends of the auxiliary cylinder connected by a common pipe, which serves as a by-pass for the oil to flow from one end of the cylinder to the other, and vice versa. Both ends of the auxiliary cylinder have the same routines, and a valve is usually located in the by-pass, which is under the cont-rol of the operator. When the valve is closed, owing to the incompressible nature of the oil, the hoists and the weight supported thereby are held stationary. Under this arrangement the leaking of the pressure, and also the effect of the friction, may be so controlled as not to betroublesome or dangerservice, because of the additional space requiredv for installing the auxiliary parts.

My improved hoist comprises the following parts:

2 represents a central hollow plunger, cylindrical in form, its lower end having a transverse circular opening 3, to receive a shaft or other supporting part 3 for mounting the plunger in a substantially stationary manner. The plunger is preferably hollow throughout its length, the middle portion of which is enlarged, as at 4, for

providing a cylindrical rchamber or reseri voir for holding oil or other suitable liquid for use in braking and governing the hoist. Immediately above the shaft bearing 3, the bore of the -lplunger is closed by aplug or part 5, which is rigidly held in place by means of a screw G. The plug has a flange 7, which serves as a support or stop for a tubular lining 8, whichisfitted snugly and rigidly in the opposite end portions of the plunger. The tube 8 extends the full length of the plunger from the top of the plug 5 to, and terminates substantially flush with, the upper endof the plunger, and forms a cylinder for a piston 9, which connects by means of a rod 10, and is operated by, a cap or head 11 of an outer cylindrical hoisting member 12, which reciprocates on the outer surface of the piston or plunger 2. The piston 9 is made pressure tight in the cylinder 8 by means of a packing 13, which is disposed between an annular flange 14 of the piston, and a gland sleeve or ring 15. The gland 15 is held tightly against the packing 13 by means of a tube 16, which incloses the piston-rod 10. The upper end of the tube 16 receive-s a reduced depending portion 16 of the cap 11 which holds the parts concentrically. A nut 17 is fitted to the threaded upper end of the piston-rod 10, for drawing the said rod upwardly for effecting the compressing of the packing 13,v by increasing the tension between the lower end of the tube 16 and the packing gland 15. The tube 16 being prevented from upward movement by reason of its connection with the cap 11 renders the adjustment of the packing more ready and positive.

The cap or head 11 is secured to the* upper end of the cylinder 12, by means of a number of bolts 11. The cylinder 12 is preferably bored out to a greater diameter than the plunger 2, to provide a cylindrical chamber 19, to be-filled with oil or other suitable liquid employed for braking the hoist. The chamber 19 is rendered liquid tight by means of a bottom packing 20, which is compressed between glands 21 and 22. The gland 21 is provided with an outwardly extending flange 21, which is perferated to receive bolts 23, which are threaded into the bottom flange 12 of the cylinder 12. The gland 22 has a shoulder 22 which engages a corresponding shoulder of the cylinder 12, which prevents said gland from being Vforced upwardly by the tightening f of the bolts 23. The gland 22 extends upwardly between the plunger 2 and the cylinder 12 for a considerable distance, and is bored out tapering or funnel-shaped, for agreater part of its length, to provide a narrow liquid passage 24 which entirely surrounds the plunger 2. The upper end of the chamber 19 is made liquid tight by means of a packing 25, which is disposed between a lower gland 26, which rests upon a shoulder 26 of the plunger, and an upper gland 27, which is held in place and compressed by a gland-nut 27 which connects by means of threads with the upper end of the plunger 2. The tightening up of the Y glands 21 and 22, and also the glands 26 and 27 compresses the packings 20 and 25 tightly against the outer surface of the plunger 2 and the surface of the cylinder 12. The piston 9 plays reciprocally in the tube 8, at the same time the cylinder 12 moves telescopically over the outer side of the plunger 2.

The cylinder 12 and its piston 9 are preferably actuated by means of air pressure which is supplied by a hose or pipe 2S, which is inserted into a port 29 located directly beneath the upper fiange of the cylinder 12. The air after passing through the port 29 enters an annular cavity or space 30, which lies between the cap 11, the gland nut 27, and the upper end of the plunger 2. As soon as the air pressure is admitted into the chamber 30, the cylinder 12 and the piston 9 move upwardly for performing the work of the hoist.

The tube 8 separates the oil chamber 4 from the central portion of the plunger in which the piston 9 operates, and should be so fitted as to prevent the oil from passing from said chamber into the piston way.

31 and 32 represent oppositely facing integral lugs formed on the external surface of the cylinder 12, and these lugs are employed for operatively connecting the hoist with a. weight or other object to be operated or lifted. The lugs 31 and 32 are preferably perforated to receive shafts or pins 31 and 32 which may be employed for connecting the cylinder 12 with the weight. If desired, the lug 31 alone may be connected to the object to be lifted, and the lug 32 may be connected to and operate certain of the controlling parts, as a link or lever 33, shown in dotted lines in Figs. 1 and 2.

rlhe chambers 4 and 19, when the hoist is assembled ready for use, are preferably filled with heavy oil by passing the saine through a hole 19 which is then closed by a plug 19. Then the air pressure is applied to the head of the cylinder 12, which starts the said cylinder upwardly, the oil confined in the chamber 19 is displaced by the upward travel of the gland 22, which forces the oil through a port 34- into the central chamber 4. As oil is incompressible,

.the chamber 4 is provided at or near its extreme lower end with a relief or outlet port 35. The quantity of the oil which is thus displaced by the gland 22 during the upward movement of the cylinder 12, iows from chamber 4 through the port 35 into a suitable tube or pipe 36, and thence preferably passes into and through a valve, which may be of any suitable construction and arrangement, but which preferably consists of a device, as A37, which is arranged to control b'oth the air and the oil employed for the operation and governing of the hoist. The oil, as explained, after leaving the chamber 19, passes through a pipe 36, thence through the valve 37, and is carried by a pipe 33 back to the plunger 2, where the oil passes through a port 39 in said plunger, thence through the lower end of the tube 8, into an angular passage 40 formed in the plug 5. The plug 5 has an upwardly extending tubular part or nozzle 41, which, when the hoist is closed up or is at rest, is disposed in a narrow cylindrical chamber 42 which is formed in the lower end of the piston 9. The nozzle 41 is preferably tapered externally, and throughout its entire length is preferably of smaller diameter than the chamber 42 of the piston, so as to provide a normally open passage around the said nozzle which communicates with a small annular cavity 43 which lies between the lower end of the piston 9 and the top of the plug 5. When the oil enters the hollow portion of the plug 5, it rises and flows over the top of the nozzle, and passes downwardly through the space between the nozzle and the piston, and enters the chamber 43. Then as the piston 9 and the cylinder 12 are moved upwardly by the force of the air pressure, the chamber 43 increases in height correspondingly, (see Fig. 2), and as the oil is displaced from the chamber 19 by the gland 22 the chamber 43 is filled. In practice, the quantity of the oil forced out of the chamber 19, is exactly the amount required to fill the chamber 43. The flow of the oil, at all times, will be relatively at the same rate or speed, as the upward movement of the cylinder 12 and its piston 9. The speed at which the hoist is operated for accomplishing its work, may be regulated to any desired degree, by the size of either of the ports 34, 35 or 39, as well as by the choking or the enlarging. of any of the several oil passages, in the hoist or in the valve.

It is desirable in a hoist of the class to which my improvement relates, to provide for the nest range or degree of adjustment, so as to obviate all jars and jolts to the device, as well as, to the objects to be lifted or moved thereby, and for this purpose, I have provided the feature of tapering the glandsleeve 22, and also the nozzle 41 of the plug 5. Under this construction and arrangement, when the gland 22 has moved upwardly its full travel, the lower extremity of the tapered portion 24 of the gland 22 is disposed opposite the port 34, which allows a constant communication between the chambers 4 and 19 for the circulation of the oil. On the other hand, the nozzle 41 being tapered its full length, provides a normally open passage between the nozzle and the piston 9 into the chamber 43. rlhe effect of these last described provisionsl is to permit the starting or stopping of the movable members of the hoist in a gradual manner wit-hout the least perceptible jar or jolt.

The hoist, as stated, is controlled by the valve, 37 which is preferably arranged to be manually operated for simultaneously opening and closing the compressed air and the oil passages therethrough, and which enables the operator to exercise a proper and perfect control of the hoist and all of its working parts. A brief description of the valve 37 follows: 44 represents an inner member or plug of the valve, which is arranged to operatively fit in a movable casing 45, which is provided with a bushing 46, to fit the plug 44. The casing and bushmg are provided with concentric air in-take ports 47, which receive the air pressure from a supply pipe 48, and also with air outlet ports `49. The ports 47 and 49 are so arranged when the casing and bushing are rotated toward the left as to connectwith a` curved passage 50 formed in the plug 44, which lpermits the air to pass from the supply pipe 48 into the pipe 28, by which it is delivered to the hoist. 51 represents a port which is formed in the casing and bushing of the valve which connects with the oil pipe 36, and 52 represents a port formed in the casing and bushing, vwhich `connects with the oil pipe 38. The ports 51 and 52 are arranged to connect with a by-pass 53, formed in the opposite side of the plug 44, when the casing is rotated in either direction its full movement by means of a handlever 54. Fig. 3 shows the valve 37 in open position, which allows the air pressurev t0 pass from pipe 48 through port 47 and bypass 50 into port 49, and thence into pipe 28 for lifting the hoist. At the same time the valve is set for the passage of the-air, as described, the ports 51e and 52 are made to coincide with the by-pass 53, which permits the oil, or other liquid, to flow from the chamber 4, through pipe 36, and through the valve 37, into pipe 38, which delivers the' oil to the chamber 43 of the plunger 2. To exhaust the air from the cylinder l2, for operating the hoist in the opposite direction for closing the same (see Fig. 1), the operator should swing the lever 54 to the right until the port 49 coincides with a port or passage 55, which extends from the outer side to the center of the plug 44, which will allow the air pressure to exhaust from the cylinder 12, and escape to the atmosphere through a central port 56 in the plug 44. At the same time the port 49 is shifted into communication with t-he port 55 and the supply of air .is cut off, by breaking the connection between port 47 and by-pass 50,

' and the oil ports 5l and 52 are brought into casing 45 of the valve so as to bring the port 49 between the ends of the by-pass 50, which will shut olf the supply of air, and at the same time shift the port 51 out of commimicvation with the by-pass 53, and thus prevent the displacing of the oil confined in the piston chamber 43.

Under-the construction and arrangement of the parts, as described, the movements of cylinder 12 and piston 9 will at all times be governed or controlled by the rate of flow of the oil from the chamber 19 to the chamber 43, and vice versa. If the air should be exhausted without at the same time allowing the oil to be displaced from the cylinder 48, the hoist will be held in extended position by the oil. On the other hand, if the air pressure is exhausted by leaking out of the cylinder 12, at a time when the oil ports are all open, the hoist will close up in a gradual manner, or at a speed governed by the rate of flow of the oil, from the chamber 43 back to the chamber 19. In either case the hoist will be perfectly governed and cont-rolled and all jarring, jolting, and jerking will be obviated by the use of the oil, as described. Owing to the use of the oil for the braking and governing of the hoist, the device, o-r its working parts are practically self-lubricating and require no special means for the purpose.

It is obvious that some changes or modifications may be made in the parts of the device without departing from the spirit of my invention, and I therefore do not restrict myself to the precise* construction, arrangement and operation, as herein shown and described.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent, is-

1. In combination, a stationary plunger having a cylinder arranged therein, and having a cylindrical liquid chamber encircling the said cylinder, a piston in said cylinder, a conduit for carrying a liquid from said chamber to said cylinder beneath the pist-on, a movable cylinder telescopically fitting the outer surface of the plunger, said movable cylinder connected with and adapted to actuate said piston, and a pipe for supplying a Huid pressure for elevating said movable cylinder.

2. In combination a stationary plunger, having a cylinder arranged therein, and having a liquid chamber encircling said cylinder, a piston in said cylinder adapted to be cushioned by liquid received from said chamber, a conduit for conducting liquid from said chamber to said cylinder beneath the piston, a lifting cylinder telescopically fitting the outer surface of said plunger, said lifting cylinder connected with and adapted to actuate said'piston, and means for elevating said lifting cylinder.

3. A hoist, comprising a stationary plunger having a central cylinder and having a liquid chamber encircling said cylinder, a conduit for connecting the liquid chamber with the bottom of the central cylinder, a piston in said cylinder, a lifting cylinder telescopically mounted on said plunger and operatively connected with said' piston, a pipe for supplying a fluid pressure for moving said lifting cylinder in one direction for hoisting an object, means for exhausting the fluid pressure for permitting the lifting cylinder to be moved in the opposite direction by gravity, and a liquid carried by said chamber adapted to enter said cylinder through said conduit during the hoisting operation for cushioning the said piston and for controlling the speed at which said lifting cylinder travels.

4. A hoist, comprising a stationary member having a central cylinder, and having a chamber encircling said cylinder normally filled with liquid, a conduit connecting said chamber with the bottom of said cylinder, a piston in said cylinder, said piston normally in contact with and cushioned by a body of liquid in the bottom of said cylinder, a lifting cylinder telescopically mounted on said member and operatively connected with said piston, a fluid pressure means for actuating said lifting cylinder for hoisting an object, means for effecting the operation of said lifting cylinder in the opposite direction by gravity, and means for regulating the fiow of the liquid from said chamber to said central cylinder and vice versa for controlling the speed of said lifting cylinder and said piston.

5. In combination, a stationary plunger having a central cylinder therein, a piston in said cylinder, a reciprocating outer cylinder telescopically fitting said plunger, said outer cylinder connected to and adapted to operate said piston, a fluid pressure means for actuating said outer cylinder and said piston in one direction, and means for eilecting the operation of said outer cylinder and said piston in the opposite direction by gravity.

6. In combination, a stationary plunger having a cylinder arranged centrally therein, a piston in said cylinder, said piston adapted to be cushioned by a liquid supplied to the bottom of said cylinder, and normally engaging the lower end of said piston, a. movable hoisting member loosely telescoping said plunger for providing a cylindrical liquid chamber encircling said plunger, said hoisting member operatively connected to said piston, means for elevating said hoisting member, means carried by said hoisting member .for forcing the liquid in said chamber into the piston cylinder, for controlling the speed of travel of said hoisting member, and means actuated by the gravitation of said hoisting member for forcing the liquid back into said chamber for eecting the return movement of said hoisting member at the same speed as the first movement.

7. In combination, a stationary inner member, and a movable outer member telescopically connected thereto, the stationary member bored out, and having a concentric cylinder surrounded by a liquid chamber, a piston in said cylinder, the bottom of said cylinder comprising a reservoir, said reservoir filled with liquid for cushioning said piston during its reciprocating movements, the said outer member loosely littin g the stationary member for providing a liquid space surrounding the stationary member, said space connected with said liquid chamber by means of a port, a series of pipes for conducting the liquid from said chamber to said reservoir beneath the piston and vice versa., means for lifting said outer member, and a valve for permitting or preventing the flow of the liquid.

S. In a hoisting device, the combination of a movable outer member, and a stationary inner member, the outer member adapted for reciprocating on the inner member, a

liquid interposed between said members for braking and governing said outer member,

said stationary member having a hollow ini terior comprising a piston cylinder, the bottom of said cylinder filled with liquid, a piston in said cylinder, said piston connected with said outer member and movable therewith, the said piston contacting with the oil in said cylinder, means for admitting a fluid pressure between the adjacent ends of said members, for actuating said outer mem'- ber for hoisting an object, means for forcing the liquid disposed between the said members into the piston cylinder during the hoisting operation, and means for returning the liquid to the space between said members at the end of each hoisting operation.

9. A hoisting device comprising a hollow lifting member, and a fixed hollow plunger telescopically fitting in said member, the said parts adapted to be extended by means of a fluid pressure, and to be moved in the opposite direction by gravity, a liquidchamber arranged between said member and said plunger, a second liquid chamber disposed concentrically within said plunger, said chambers connected by means of a port, a central cylinder in said plunger, a piston in said cylinder, operatively connected with said movable member, a conduit connecting the second chamber with the lower part of the piston cylinder, a valve for controlling the fluid pressure for operating said movable member in one direction, said valve capable of simultaneously controlling a body of liquid which flows from the first chamber through the second chamber into the said piston cylinder, and vice versa, for braking and steadying said movable member during the operation of the hoist. n

10. A hoisting device, comprising a stationary plunger having a central piston cylinder and a concentric chamber for liquid surrounding said cylinder, a piston in said cylinder, a movable lifting member telescopically mounted on said cylinder, the said lifting member connected with and adapted to reciprocate said piston, a liquid space arranged between said lifting member and said plunger, means for forcing the liquid in said space through the said chamber and into the lower part of said cylinder when the lifting member and said pist-on are moved upwardly for hoisting an object, the said liquid adapted to be forced back into said space by the said piston when said lifting member is moved in the opposite direction, and means for elevating the lifting member.

l1. A hoist, comprising an inner stationary member, bored outl to provide a central cylinder and a concentric liquid chamber surrounding said cylinder, an outer reciprocating cylinder telescoping said member, adapted to be operated away from said member by a fluid pressure and to be operated in the'v opposite direction by gravity, the said outer cylinder loosely fitting said inner member for providing a cylindrical space inder for cushioning the said piston, for 105 braking and governing the movable parts of the hoist, the said liquid adapted to be forced back into said chamber and said space by the gravitation of said outer cylinder, for effecting t-he return movement thereof at the same speed as the outward movement of said part. 1

12. A hoist, comprising a stationary plunger having a central cylinder, a piston in said cylinder, a lifting cylinder telescopically mounted on said plunger and operatively connected with said piston, said lifting cylinder adapted to be moved in one direction by a fluid-pressure for hoisting an object, and to be moved in the opposite direction by gravity, means for cushioning t-he said piston for controlling the speed at which said lifting cylinder travels, and a valve for simultaneously controlling the fluid pressure and the cushioning means.

13. A hoist, comprising a stationary plunger having a central piston cylinder and a concentric liquid chamber surrounding said cylinder, a piston in said cylinder disposed so as `to provide a liquid reservoir in the bottom of cylinder, a lifting cylinder reciprocable on said plunger by means of a fluid pressure, the said lifting cylinder connected with and adapted to operate said piston, for enlarging and contracting said reservoir, the said lifting cylinder loosely fitting the said plunger, for providing an outer liquid chamber which connects with the first named chamber by means of a port, and means carried by the lifting cylinder for forcing the oil carried by the said chambers into the reservoir beneath the piston.

14. A hoist, comprising a stationary plunger, and a telescoping lifting cylinder reciprocally mounted on one end of the plunger, the lifting cylinder loosely fitting the said plunger for providing` a cylindrical outer oil chamber between said cylinder and said plunger, the said plunger bored out lengt-hwise for providing a central piston cylinder and an inner oil chamber surrounding said cylinder, the said chambers communicating by means of a port, the lifting cylinder adapted to be extended longitudinally on the plunger by means of compressed air, means carried by the lifting cylinder adapted .when said cylinder is moved by the air pressure to force the oil from the outer into the inner chamber, a conduit for connecting the inner oil chamber to the lower part of the piston cylinder, a piston in said piston cylinder connected to and operated by the lifting cylinder, the space below said piston comprising a reservoir adapted to receive the oil displaced from the said chambers when the hoist is actuated by the air pressure, the said lifting cylinder adapted to be moved in the opposite direction by gravity when the air pressure is exhausted, and means for forcing the oil from the said reservoir back into the said chambers during the gravitation of the lifting cylinder.

l5. In a device of the character described, the combination of a stationary plunger the center of which comprises a cylinder, a piston in said cylinder and a reservoir arranged in said cylinder' beneath the piston, an outer movable, member telescopically mounted on said plunger, said member connected to and adapted to act-nate said piston, said member loosely fitting said plunger for providing a cylindrical space for holding a liquid, a conduit for conducting the liquid from said space to said reservoir for cushioning and braking the said piston and said member during their reciprocating operations, and means for elevating said outer member.

In testimony whereof I aflix my signature in presence of two witnesses.

MERRILL DAVIS. Witnesses CHAS. A. D'UNHAM, P. NORTON.

Copies of this patent may be obtained for ve cents each, by addressing the Commissioner of Patents Washington, D. C. 

